Internal combustion engines convert chemical energy from the supplied fuel in the form of gasoline, diesel, propane, natural gas, alcohol or some combination thereof to mechanical energy to drive the engine.
Most internal combustion engines employ a cooling system to circulate coolant through the engine. The coolant serves to remove heat from the engine in operation thereby preserving the engine materials and the gaskets from overheating and consequently failing. The coolant path in an engine begins from the water pump. The path continues through the crankcase and cylinder head, branching along the way to other components that may be present, such as the oil cooler and the exhaust gas recirculation (EGR) system. The coolant exits the engine into the radiator through the thermostat. In the radiator, the heat in the coolant is extracted into the environment so that the coolant returns to the water pump from the radiator at a relatively cooler temperature than when the same coolant left the thermostat to go into the radiator.
Internal combustion engines typically possess a thermostat port in the cylinder head or just outside the cylinder block, before the radiator inlet. The typical arrangement of the thermostat port and the thermostat bypass port in the cylinder head is such that the bypass and the main flow ports are in-line with the coolant flow. The typical thermostat design uses up nearly one third of the pressure developed at the water pump to overcome the constriction inherent in the thermostat design. Also, in traditional thermostat design, there is a by-pass flow of as much as one eighth of coolant specified flow rate when the thermostat is fully open. This, unfortunately, is typically not taken into account in the determination of the amount of coolant flowing through the thermostat.
It takes a while for the thermostat to be fully open in the traditional thermostat design. There is a continuous variable-rate surge of coolant, and the thermostat, as a result, bounces throughout engine operation even when the thermostat is fully open. Also, in the current design, especially in trucks, the architecture to contain the thermostat forces a high hood with a less-than-desirable aerodynamic design. There is a need for a more effective thermostat. Such a thermostat would have a lower pressure loss across it, would eliminate or substantially reduce the by-pass coolant flow when the thermostat is fully open, and would open and close more effectively with minimal bounce or vibration throughout an engine operation.